Displaying graphics when a disc directory is listed

There are two instructions to display a directory of a disc:

• CAT
• |DIR

The differences between these two commands are listed below.

CAT

Example output using CAT command:

cat

Drive A: user  0

CATALOG .ASM   4K   SCROLL  .BAK   2K
HWSPRITE.ASM*  4K   SPLTSCRN.ASM   3K
SCROLL  .ASM   2K

163K free

Ready

Notes:

• File names are sorted into increasing alphabetical order before display
• The file-size is displayed
• The file names are printed using firmware "TXT OUTPUT" (&BB5A) function which will execute control characters.
• A "*" character is displayed after the extension if the file is read-only. If the file is read-write then a " " (space) character is displayed.
• Hidden/system files are not displayed
• Free space remaining on disc is displayed

|DIR

Example output using |DIR command:

|dir

Drive A: user  0

HWSPRITE.ASM   CATALOG .ASM
SPLTSCRN.ASM   SCROLL  .ASM

163K free

Ready

Notes:

• File names are listed in the order stored in the directory
• File size is not displayed.
• The file names are printed using firmware "TXT OUTPUT" (&BB5A) function which will execute control characters
• read-only/read-write state is not displayed
• Hidden/system files are not displayed
• Free space remaining on disc is displayed

Displaying text and graphics using CAT and/or |DIR

The standard DATA and SYSTEM formats have 64 directory entries.

The following procedure is used to display a directory listing:

1. Display blank line
2. Display "Drive " followed by drive letter ("A" or "B")
3. Display ":" character
4. Display " user " followed by user number (the user number is displayed padded with spaces) e.g. " 0", " 15"
5. Display blank line
6. if CAT:
   • Perform directory operation and sort filenames into increasing alphabetical order
7. if |DIR:
   • Perform directory operation and do not sort
8. The following procedure is repeated for each filename:
   • Display the 8 characters of the name part of the filename
   • Display a "." character
   • Display the 3 characters of the extension part of the filename
   • If |DIR
     • display 3 spaces
   • if CAT
     • If file is read-only, display a "*" character, otherwise if file is read-write display a " " (space) character.
     • display 2 spaces
     • display file size in K, followed by "K" character

If you want the output to look identical with CAT and |DIR, follow these rules:

• List the directory entries in the order that they are "executed"
• Do not use the extra characters ("*" and file size) displayed by CAT, or the 3 spaces displayed by |DIR

Offset	Count	Description
0	1	User number (set to "0")
1	1	Sort key (use the characters with ASCII codes 32-127 in ascending order)
2	1	ACK control code (enable printing of characters)
3..8	6	(useable)
9	6	BS (to erase "." character)
10	1	(useable)
11	1	NAK
12..31	19	not used (set to "0")